In recent years, there are beginning to prevail electric vehicles and hybrid vehicles which include devices such as motors and batteries and which travel by driving the motors, using power accumulated in the batteries. Electric vehicles need to have their batteries charged by external feeding devices, and even in the case of hybrid vehicles, there are plug-in hybrid vehicles that allow their batteries to be charged by external feeding devices. In a vehicle whose battery is charged from outside, a plug of a charging cable connected to an external feeding device is coupled to a connector device of a charging port provided in the vehicle, and power is supplied from the feeding device to the battery of the vehicle via the charging cable, whereby the battery is charged.
On the other hand, in the case of charging a battery of a vehicle by a feeding device, a communication function is required that allows transmission and reception of information for controlling the charge and information for managing the amount of charge, accounting, etc. between the vehicle and the feeding device. For communication between the vehicle and the feeding device, it is conceivable to use power line communication via a charging cable.
Patent Literature 1 proposes a power line carrier device configured such that data of a frame length of Ethernet is converted into fixed packets shorter than this frame length, to be converted into power line carrier signals using each packet as a unit, thereby performing communication using a power line, and when a communication error occurs, packets are transmitted again. Accordingly, the power line carrier device has an enhanced throughput.
Conventional power line communication devices typically employ a configuration in which two power lines are each branched to have a branch line, and an electromagnetic induction type signal converter (a circuit element such as a coupling transformer) which superimposes and separates a signal on and from the power lines is connected to the branch lines (that is, a coupling transformer or the like is connected to and between the two power lines). The power line carrier device described in Patent Literature 1 has a similar configuration to the above.